Evaluation of the water quality related to the acid mine drainage of an abandoned mercury mine (Alaşehir, Turkey)

Mobility of metals in water, mine wastes, and stream sediments around the abandoned Alaşehir mercury mine was investigated to evaluate the environmental effects around the area. Mine waters are dominantly acidic with pH values of 2.55 in arid season and 2.70 in wet season and are sulfate rich. Acidity is caused mainly by the oxidation of sulfide minerals. Pyrite is the main acid-producing mineral in the Alaşehir area. Of the major ions, SO₄ shows a notable increase reaching 3981 mg/l, which exceeds the WHO (WHO guidelines for drinking water quality, vol. 2. Health criteria and other supporting information, 1993) and TS (Sular-İçme ve kullanma suları. Ankara: Türk Standartları Enstitüsü, 1997) drinking water standard of 250 mg/L. Mine waters have As, Fe, Mn, Ni, and Al with concentrations higher than drinking water standards. Hg concentrations of adit water samples and surface waters draining the mine area are between 0.25 and 0.274 μg/L and are below the WHO (WHO guidelines for drinking water quality, vol. 2. Health criteria and other supporting information, 1993) drinking water standard of 1.0 μg/L. However, the concentrations are above the 0.012 μg/L standard (EPA, Water quality standards. Establishment of numeric criteria for priority toxic pollutants, states' compliance, final rule. Fed. Reg., 40 CFR, Part 131, 57/246, 60847-60916, 1992) used to protect aquatic life. Stream sediment samples have abnormally high values of especially Hg, As, Ni, and Cr metals. Geoaccumulation (Igeo) and pollution index (PI) values are significantly high and denote heavy contamination in stream sediments. The stream sediments derived from the mining area with the surface waters are potentially hazardous to the environment adjacent to the abandoned Hg mine and are in need of remediation.